Centralized traffic control system for railroads



Oct. 17, 1950 F. T. PASCOE CENTRALIZED TRAFFIC CONTROL SYSTEM FOR RAILROADS Filed m 17, 1947 5 Sheets-Sheet 1 v NW N m :m

INVENTOR 7. Pas'coe.

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rramvzy Oct. 17, 1950 F. T. PASCOE CENTRALIZED TRAFFIC CONTROL SYSTEM FOR RAILROADS Filed Jul 17, 1947 F. T. PASCOE ,526,404

CENTRALIZED. TRAFFIC CONTROL SYSTEM FOR RAILROADS Oct. 17, 1950 5 Sheets-Sheeii 3 Filed July 17, 1947 a a I I ZLA 12 A71 1 C a M77? MT! 347 3 MES I I KEJ' 6 INVENTOR. 17nd 7? Pascoe.

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1575 ATTOBNI'I Oct. 17, 1950 F. T. PASCOE 2,526,404

CENTRALIZED TRAFFIC CONTROL SYSTEM FOR RAILROADS Filed July 17, 1947 5 Sheets-Sheet 4 m mq WHHUWMHMHHHHHHH |||l| ll ||||ls|llwlllllunwwlfiwl-llllllllil ||1||||| Ilull 1 1 I.

s 4 B A -F d WES 1 1 20 w. xx 5 'INYENTOR if?! 7. Pmoe. BY

' H15 ATTORNEY F. T. PASCOE Oct. 17, 1950 CENTRALIZED TRAFFIC CONTROL SYSTEM FOR RAILROADS Filed July 1'7, 1947 5 Sheets-Sheet 5 INVENTOR. I]? Z Pascoe; BY

Patented Oct. "17, 195

UNITED... STATES PATENT orrlce CENTRALIZED TRAFFIC CONTROL SYSTEM ronnAinnoaos 7 Frank T. Pascoe, Carnegie, Pa., assignor to The Union Switch & Signal Gompany Swissvale,

Pa.,.a. corporation of Pennsylvania Applicationluly 17, 1947', Serial No. 731,667

-My invention relates to'centra-lizedtraffic control systems for railroads, and more particularly to apparatus or controlling the movement of traffic on stretches of railway track over which traific may move in either direction and for selecting the direction of traffic 'movementon'either of two parallel. tracks such as those comprising the passing tracks which interconnect the successive stretches of single track on single track railroads.

The principal 'object'of my invention is the provision of an improved system for the remote control from a, central omceof'a coded reversible signaling system of the type illustrated in the United States Letters Patent No. 2,390,010, is.- sued November 27, l945,'to Talbert and Staples, but my invention also includes improvements in the wayside circuits-of the system of the patent by which the control from the central ofiice is facilitated and improved operation obtained.

The signaling'system of this patent is arranged to provide reversible coded track circuit control for those railway signals located at the ends of the passing tracks, which govern the movement of trains into the main track and into the siding, respectively, from the adjoining single track stretches at either end, and is arranged for use in a block signaling system'in which the signals which govern traffic movements through the single track blocks are also controlled by coded track circuits, a system for that purpose being shown, for example, in the United States Letters Patent No. 2,344,333, issued March 14, 1944, to J. J. Van Horn, which patent was reissued as No.

Re. 22,780 on August 13, 1946. These two systems together provide coded track circuits for all track in th controlled territory except for the short detector sections which include the track switches at the ends of the p'assingtracks. The coded track circuits not only control the railway signals but in addition provide a system'for the control of motor car indicators and for that purpose each coded track circuit is arranged to be norma 1y energized by steady current except when a train movement is authorized. As explained in the Talbert and Staples patent, each motor car or hand car used by maintainers or others in the controlled territory is provided with insulated wheels across which an indicator lamp. is connected so as to-be normally lighted by 58Claims. (Cl-2.4593) current in the track rails. The flashing of this lamp when the track current is coded indicates to the operator of thecar that "a train may be 2 -The remote control system by which the track switches and signals are manually governed from the control ofiice is to be understood to be of the Ti-me Code type as described in the United, States Letters Patent No. 2,411,375," issued 'N olever for the entering signal, only when the op-' eration of a trafiic relay at the exit end of the block. is required in order to efiect the clearing of such signal. A, further feature, of my inven tion is the provision of means for controlling-the order of transmission of the two codes referred to so that the one for operating the trailic relay is not issued until the signal control relay at the opposite'end oi the block has been reversed. In respect to this feature, my invention is an im-' provement upon that disclosed in a copending application for United States Letters Patent, Serial No. 708,920, filed November 9, 1946, by F. T. Passes and A. L. Jerome.

One form of apparatus embodying my invention will now be described and the novel features thereof will then be pointed out in claims.

Referring to the accompanying drawings, Fig. 1 shows the apparatus at the control oflice, comprising a miniature track diagram of the controlled'territory together with the control panels for the two stations of the remote control system at opposite ends of the passing tracks shown in the diagram, while Figs. 2A, 2B, 2C and 2D, when arranged side by side in the order listed, form a view of the corresponding track plan together with the relays and apparatus at each of the two stations.

As shown in the drawings, the controlled territory includes the detector sections T and 3T; for the power operated track switches lW andBW together with the intervening double track stretch comprising the track sections AT and ET. The latter are equipped with oppositely directed coded track circuit systems of the type shown in the above-mentioned Talbert and Staples patent, one of which systems controls the opposing main line signals ZRA and SL-A, which govern train .movements through section AT, and the other the opposing slow speed signals 2RBgand G'LB which govern train movements into the side track section BT.

. 3 signals ZLA, ZLB, lRA and tRB are not shown, but these may be of the type shown in the Van Horn patent above referred to'.

The detector sections IT and 3T are each provided with a conventional track circuit having a track relay ITR or 3TB, normally energized by a track battery TB and controlling a slow acting track repeater relay ITP or 3TP, while the coded track circuit sections AT and BT are each provided with a set of code transmitting and detecting apparatus at each end. As shown in Fig. 2C, a code transmitter relay LACT is normally energized over a circuit extending from one terminal B of the local source of energy over back contact of a directional control relay LAPS and the normal contact a of a polar stick traflic relay LAFS through relay LACT to the other terminal C of the local source. Contact a of relay LACT normally connects a track battery TB through relay LATR to the rails of section AT to supply steady current thereto which holds the-track relay RATR, Fig. 2B, steadily energized, and relay RATR in turn holds a slow release front'contact repeater relay RATF energized. Similarly, in Fig. 2B the code transmitter relay RBCT is normally energized over back contact 0 of a directional control relay RBPS and contact a of a polar stick traflic relay RBFS, its circuit also including a back contact 0 of a directional stick relay REDS, and relay RBCT supplies energy normally from a track battery TB through relay RBTR to the rails of section ET by which the track relay LBTR and its front contact re- Referring to Fig. 1, the relays ITK, BTK, ATK

and BTK are indication relays governed over code channels identified by the numbers Ill and I2, with suflix a or b, by indication codes transmitted from the field stations by the remote control system of the Jackel patent hereinbefore referred to. Relays ITK and 3TK are track indication relays which are picked up over channels Illa and lllb upon the release of indication storage relays ITKS and 3TKS controlled by relays ITP and 3TP, as shown in Figs. 2A and 2D, respectively, and indicate the occupancy ,of the detector section IT or 3T by the lighting of lamp ITKE or 3TKE in the track diagram, while relays ATK and BTK are block indication relays which are picked up over channels 12a and [2b upon the release of relays RATF and LBTF to indicate the occupany of the block sections AT and ET by the lighting of lamps AKE and BKE, all of these lamps being normally dark, as shown.

Another function of the code controlled indication relays is to render the control codes inefiective to change the condition of the track circuit system when any of the track sections involved is occupied, back contacts b, c, d and e of these relays being included in the control circuits of Fig. 1 for that purpose.

The control apparatus of Fig. 1 includes two individual panels for the control of the wayside apparatus, that at the left being for the control, of the apparatus of Figs. 2A and 2B as indicated, this including a switch lever ISW, a signal lever ZSG, and a starting button ZSTB controlling a starting relay 2ST together with a selector relay 234s which is operated in response to a control code initiated by relay 2ST to establish a plurality of control channels, and a delivery relay 234D, by which the indication relays are operated in response to an indication code received from the station of Figs. 2A and 2B. The right-hand panel includes a similar set of apparatus for the control of the wayside apparatus of Figs. 2C and 2D. All of this control apparatus is identified by reference characters similar to those of corresponding elements in the Jackel patent and functions as described therein.

In addition, Fig. 1 includes two auxiliary or storing relays ZSTS and 4STS, each of which is picked up by the operation of the starting button of the corresponding panel but only if the positions of the switch and signal levers of the panel indicate that the operation of a traffic relay controlled from the other panel is required and that the transmission of two codes is required to set up the desired route. The operation of the storing relay serves to initiate the transmission of the two codes and also insures their. transmission in the required order.

The central office control of the track switches is effected b the operation of polar stick control relays IWS, Fig. 2A, and 3WS, Fig. 2D, over the control channels la and 3a, or lb and 3b, by the switch levers ISW and SSW, and the signals associated therewith are governed by the operation of signal control relays 2LI-IS, 2RHS, 4Ll-IS, and 4RHS controlled over channels 5a and la, or 52) and lb, by the signal levers ZSG and 4SG in the manner described in the Jackel patent. In addition, the remote control system is arranged to operate the traffic relay LAFS, Fig. 2C, and the similar relay RBFS, Fig. 2B, from normal to reverse by the energization of channel 4b or 4a during the transmission of control codes to their respective stations, but these tralfic relays are not restorable to normal by code transmission, but only b the energization of the adjacent track relays in response to current received over the track rails from the remote end of the block. Each of these trafiic relays controls a slow release repeater relay LAFSP or RBFSP by which it is interlocked with the directional control relay LAPS or RBPS which governs the opposite direction of traffic movement.

Each of the track switches IW and 3W has associated therewith a polarized indication relay such as relay IWP, Fig. 2A, which is energized in its normal or reverse position only when the switch is locked in a, corresponding position, which relay jointly with the associated switch control relay controls normal and reverse switch indication relays such as the relays INWP and IRWP. The switch machines for switches [W and 3W are of the dual control type provided with a selector lever IDS or 3DS by which the switch machine may be conditioned for either hand or power operation, each selector relay controlling a repeating relay IWLS or 3WLS which is energized only when the switch is conditioned for power operation.

The signals as shown are of the searchlight 7 type each having three position mechanisms identified by the letter G prefixed by the signal designation. Each signal mechanism in its deenergized or stop position displays ared light, and, when energized in the direction indicated by the legend Y or G, operates the corresponding circuit controller contacts and displays a yellow or greenlight to indicate caution or proceed, re-

spectively. Each group of mechanisms in the stop position energizes an indication relay ERGP, ZLGP, lRGP or ALGP and the mechanisms ELAG and tRAG ,for the main line signals ZLA and RA control repeating relays 2LAHP and c-RAI-IP b means of which the cautionand proceed aspects of signals ALA and ZRAloc-ated in the rear of signals ALA and ZRA, respectively, are contro1led. Each group of signal mechanisms is controlled by a block repeater or route relay ZRBF, Fig. 2A, or ELBP, Fig. 2D, governed by the 7 corresponding signal control relay 'EBI-IS or @1158,

and also by code detector or decoding relays oi the coded track circuit system such as relays ZRAI-I, and QRBD, or lLAI-I and :lLBD, and by a directional stick relay such as relay REDS .or LBDS. Each group of signals has associated therewith a conventional approach locking stick Y relay such as relay QRAS or ZLAS, Fig. 2A, or relay lR-AS or this, Fig. 21), having back contacts in the circuits for the associated signal mechanisms and front contacts in the circuits for controlling the adjacent track switch and in circuits which control opposing signals. A time element relay such as iTER or BTER. is provided whereby the energizatio-n of each approach locking relay is delayed for an appropriate time interval following the manual return of one of the associated signals to its stop position. The approach lockingrelays 2RAS and iLAS also govern section locking relays RAES, Fig. 2B, and LBW S, Fig. 2C, for the detector sections IT and 3T.

Continuously operating code transmitters ltECT and l'ECT are provided at each station which generate coded currents having substantially equal on and off periods by the continuous opera tion of their contacts at a constant rate of 180 or '75 times per minute, respectively.

In response to the reversal of the trafiic relay LAFS, Fig. 20, by the operator, the circuit for holding rela LACT steadily energized is opened and relay LACT is caused to operate periodically to supply coded current to section AT at its righthand end by supplying coded current to relay LACT over the circuit extending from terminal 33 at contact of relay ALAS, Fig. 2D, over contact e of relay 3'1? and contact I) of relay 3WLS to wire 2!, or from terminal B over contacts b of relays SRWS and 3WLS to wire 2!, and thence over contact a. of the code transmitter I8'3CT or i501, Fig. 2C, contact a of the repeating relay dRAI-IP for signal ARA, the reverse contact a of relay LAFS through relay LACT to terminal C. Relay RAI-IP is controlled by the mechanism for signal QRA so that 75 code is supplied to section AT when signal RA is at stop and 130 code when signal lRA indicates caution or proceed.

The energization of section AT in the opposite direction by coded current is governed by the entering end signal control relay lLI-IS of Fig. 2D. The reversal of relay 4LHS when relay LAFS is normal completes a circuit for the directional control relay LAPS from terminal B over contacts c, of relays lLl-IS and SNWP, Wire 22, back contact a of rela LAFSP, normal contact 0 of relay LAFS through relay LAPS to terminal C, and relay LAPS becomes energized and its back contact c opensto release the normally energized relay LACT and thereby discontinue the supply of steady current to the rails of section AT. The track relay RATE, of Fig. 2B therefore releases, deenergizing the slow release repeating relay RATF and energizing a. slow release back contact repeating relay RATB, and upon the release of relay RATF, a slow release trafilc relay RAFS is which serves t restore the traffic relay LAFS to normal when section AT is vacated and thereby 6 picked up over thecircuit extendin from termt rial B over contacts a of relays RATE, RATF,

and RATB, Cont 0 of r lay RAES through relay 7 RAFS to terminal C. Relay BAFS then completes a stick circuit at its contact a, and by closing its front contact I;- completes a circuit for effectin the periodic operation of relay RACT whereby section AT is supplied with '75 code when signal ZLA is at stop and with code when signal ZLA indicates caution or proceed. This circuit extends fro-mterminal B at front contact I; of relay EWLS, Fig. 2A, over wire 23, back contact b of relay RATR over contact-c of the code transmitter ltlCT to back contact a ofrfilay ZLAl-TP or from wire 25 over contact a of the code transmitter ESllCT to the front contact a of relay ZLAHP and thence over front contact I) of relay RAFS, wire 2% and contact 9 of relay IRWP to wire 2%, or from wire 2 3 over contact I) of relay RAES, wire 25, and contact e of rela ETP to wire 26 and thence through relay RACT to terminal 0.

The code followin track relays LATE and RATE govern decoding apparatus which is generally similar to that of the Talbert and Staples patent referred to. When relay LATR is operated periodically, relay LATE is maintained picked up by periodic energization over contact a of relay llATl-t and ccmpletesa circuit from terminal B at its contact a over contact 0 of relay LATR to energize the primary winding of the decoding transformer DTil in such a manner as to cause current of the code frequency to be induced in the lower winding of transformer UT? and the latter current is rectified by contact d of relay LATR to energize the code detector rela GLAH. When the operation is at the 180 code rate, the decoding relay aLAD is also energized, through the selective decoding unit iSElDU.

When relay RATR is operated periodically, the slow release relays RATF and RATB are maintained picked up by their alternate energization over contact a of relay RATR and if relay RAFS is released, the decoding transformer DTI is energized over back contact 0 of relay RAFS and front contact 0 of relay RATB to render relays ZRAH and ZRAD responsive to the code operation of relay RATR.

Each decodin transformer is provided with a feed back circuit by which impulses of brief duration may be supplied to the track rails during each off period of the received master code. Transformer D'Il, for example, supplies impulses through an impulse transformer J I to briefly energize the associated code transmitter relay RACT during each ofi period of the master code generated by relay LACT. Feed back impulses are supplied to section AT by the periodic energization of relay RACT over a circuit extendin from the upper terminal of transformer J5 over contacts 2; of relays RATE and RAFS and thence over wires 2d and 28 or M, 25 and 26, as already traced, through relay RACT to terminal C, and thence over the normal contact 2) of the signal control relay ERHS or front contact I) of relay lRWP and wire 2? to the lower terminal of transformer J i.

' lfl'iese feed back impulses operate the track relay LATR during the intervals between the impulses of master code supplied by relay LACT, with the result that energy is supplied over contact b of relay LATR to the lower winding of relay LAFS,

terminate the code operation of relay LACT, following a left to right train movement over themain track. When section AT is being supplied 7 code causes transformer DT3 to supply feed back impulses to relay LACT through transformer J3 over front contact of relay LAPS and the normal contact a of relay LAFS. Relay LACT therefore supplies feed back impulses to section AT which operate the track relay RATR during the intervals between the impulses of master code supplied by relay RACT. The purpose of the feed back impulses in this case is to maintain relay RATF picked up so as to disconnect terminal B at its contact b from the indication channel l2a, the energization of which causes the occupied condition of section AT to be indicated at the office. Contact a of the track rela RATR over which relay RATF is energized is closed by the feed back impulses for a small part of each code frequency cycle, and to provide full energization of relay RATF under this condition a snubbing condenser is connected in parallel with its winding over the front contact at of relay RAFS, as shown.

It will be seen, therefore, that the block indication is controlled by master code for one direction of trafiic movement and by feed back code for the other direction, and that the feed back code for said one direction serves as a means for restoring the trafilc relay to normal at the distant end of the block while for the other direction, the trafiic relay is restored by the substitution of stead current for the coded current.

Only slow speed train movements are provided for through section BT, and this section is arranged to be supplied with code only, by the transmitter relays RBCT and LBCT, to energize the decoding relays 4LBD and ZRBD, respectively, by the operation of apparatus generally similar to that provided for section AT by which the relays ZRAH and 2LAH are controlled, the energization of relay lLBD or 2RBD causing the corresponding signal 4LB or 2RB to display a green light below the red light of the main signal to indicate proceed at slow speed. When a train governed by signal ALB or 2RB enters the route governed thereby, the directional stick relay LBDS or RBDS becomes energized to maintain the established direction until section ET is vacated, and prepares circuits by which the entering. signal 'for that direction may be caused to display a yellow light below the red light of the main signal to indicate caution, slow speed to permit a train to enter the siding occupied by a preceding train moving in the same direction.

The coded track circuit system for section ET in other respects is generally similar to that for section AT, except that it is oppositely directed so as to employ code channels 4a and l2b governed by different coding units of the remote control system for the control of the trafiic relay RBFS, Fig. 2B, and for the control of the block indication relay BTK, Fig. 1.

The operation of the system of my invention will now be described under difierent assumed conditions, starting with the apparatus in its normal inactive condition as shown in each instance.

To clear signal 4LA, the operator moves lever lSG to its left-hand position with lever SSW normal, as shown, and presses the starting button 4STB, thereby energizing the starting relay 4ST. Relay ASTS is not operated because its circuit is open at contact 0 of lever SSW. The closing of contact I) of relay 4ST supplies energy to a wire 26! which initiates the transmission of a control code as described in the Jackel patent.

this code having the code call 261 by which the ofiice selector relay 2618 is energized to release relay 4ST, and channel 5b is energized over contact g of relay 261s and the left-hand contact a of lever 45G to effect the operation of relay QLHS in Fig. 2D to its reverse position, thereby energizing relay over wire 22, and relay LAPS releases relay LACT to disconnect the track battery from the right-hand end of section AT.

Relay RATR therefore releases, energizing relay RATB, and then relay RATF releases, energizing relay RAFS, which initiates the operation of relay RACT. If relay ZLAHP is released, relay RACT is caused to supply 75 code to the rails of section AT at the left-hand end, and the operation of relay LATR in response to this code picks up relay LATF, which energizes the decoding transformer DT3, causing relay lLAH to become energized. Relay LACT is operated by feed back impulses supplied by transformer DT3, so that relay RATF is energized to disconnect terminal B from channel 52a and to initiate the transmission of an indication code by which relay ATK is released and lamp AKE extinguished.

Relay iLAH now energizes the route relay LBP by completing a circuit from terminal B over contacts e of relays 3TB. and SWLS, wire 28, contact a of relay lLAH, wire 29, contacts a of relays 4RI-IS and 3NWP, contact e of relay 3WP, reverse contact a of relay ALI-IS through relay lLBP to terminal C. The opening of back contact a of relay LBP releases the approach locking relay 4LAS, and the closing of back contact c of relay lLAS completes a circuit for mechanism LAG which may be traced from terminal 13' at front contact a of relay 4LBP over front contact 0 of relay QRAS, back contact b of relay 3TER, back contact c of relay 4LAS, left-hand contact (1 of relay SWP, wire 30, back contact d of relay 4LAD, wire 32, through the winding of mechanism 4LAG, wire 3|, back contact b of relay 4LAD, wire 33, contact I) of relay 4LBP, and contacts 0 of relays 4LHS and lRHS to terminal C, causing signal 4LA to indicate caution and releasing relay dLGP.

In the event signal 2LA indicates caution or proceed, relay ZLAI-IP is energized and I code is supplied to section AT by relay RACT. In that case, relay 2LAD is energized along with relay ZLAH and contacts b and d of relay 2LAD are picked up to reverse the polarity of the current supplied to mechanism ZLAG, causing signal ZLA to indicate proceed. When the train governed by signal 4LA enters section 3T, relay 3TR and its repeating relay 3TP release, releasing relay 3TKS to connect terminal B to channel [0b and to initiate the transmission of an indication code as described in the Jackel patent, by which relay 3TK is energized to light lamp 3TKE in the track diagram. The opening of contact e of relay 3TB releases relay lLBP, which deenergizes mechanism ALAG to restore signal ALA to stop and causes relays 4LGP and ALAS to be reenergized. Relay ELI-IS is restored to normal by the energization of its lower winding over contact a of relay 3TKS, but relay LAPS which has been maintained energized over wire 22 independently of relay lLl-IS by the closing of back contact (1 of relay 4LAS is now held energized over back contact d of relay 3TP. After section ST is vacated, relay LAPS is held energized over its own front contact a and back contact I) of relay iLAI-I.

When the train enters section AT, 'the shunting of the track relay LATR stops its operation,

and relays LATF and 4LAI-I release. Transformer J3 ceases to supply feed back impulses to relay RATR, so that relay RATF releases and initiates the transmission of an indication code by which relay ATK is energized and lights lamp AKE to indicate the occupied condition of the block section AT.

After the train enters section lT, relay RACT remains released due to the opening of contact 6 of relay lTP, and when section IT is vacated, the code operation of relay RACT is resumedand if section AT is vacant, relay LATE responds to pick up relay LATE, reenergizing transformers DT3 and J3 and relay 4LAH. The opening of back ccntactb of relay 4LAH releases relay LAPS, which causes relay LACT to assume its energized position to supply energy steadily to the rails of section AT. Relay RAC T'is now being operated at the .75. code rate, and relay RATR picks up as soon as relay RACT assumes its released position. The opening of back. contact b of relay RATR holds relay RACT released, and relay RATR, therefore remains picked up, releasing relays RAFS and RATB, which con pletes the restoration of the apparatus to its normal inactive condition as shown,

To clear signal ZRA, the operator moves lever ZSG to the right with lever IS W normal and presses the starting button ZSTB to energize the starting relay 2ST, whereby a control code is initiated having the code call 234 by which the selector relay234S is energized and relay ZRHS is operated to reverse over channel la.

The reversal of the traffic relay LAFS is required in this instance and this is accomplished automatically. When button 2STB is operated, relay ZSTS is picked up along with relay 2ST over contacts a and b of button Z STB' andcontacts c of levers ZSG and. ISW. Relay ZSTS is held picked up until relay 2ST releases over a stick circuit extending toterminal B over contact a of relay EST and contact 2' of relay 234$, and to terminal C over contact a of relay ZSTS and contacts a of levers 2SG and ISW. The closing of contact c.0f relay 2STS energizes relay AST, so thatfollowing the transmission of the code 234 by relay 2ST and the release of relays ZST and ZSTS, a second code is transmitted having the code call 261. in which channel 41) is energized'over contacts b of relays ATK, ITK, and ZSTS, contacts I) of levers ISW and ZSG, contacts 6 of lever 4SG andrelay, 3TK or contact e of lever SSW, and contact 7 of relay 251s. Relay LAFS is operated to reverse over channel 412 by this second code and initiates the code operation of relay LACT, and; also energizes the slow release relay LAF'SB to maintain the circuit lWP, and the reverse contact a of relay ZRHS.

Relay ZR-BP picks'up and by openingits back cc'ntact a, releases relay ZRAS, which completes circuit for mechanism ZRAG. Assuming that e is being received, the decodingrel'ay L1 is released and the circuit for mechanism 'ZRHS to reverse.

l0 ZRAG extends from terminal B over front contact a of relay 2RBP, contact 0 of relay ELAS, contact b of relay ITER, back contact 0 ofrelay ERAS, normal contact at of relay IWP, wire 4%,back contact d of relay ZRAD, wire 50,'the windingof mechanism ZRAG, wire 5|, back contact b of relay 2RAD, wire 46, contact I) of relay ZRBP, contacts 0 of relays ZRHS and 2LHS to terminal C. In this case, mechanism ZRAG is energized in a direction to cause signal ZRA to-indicate caution, and when relay ZRAD is. energized, the polarity of the current supplied to mechanism ZRAG'is reversed to cause signal ZRA to indicate proceed. The opening of contact I; of the approach locking relay ZRAS disconnects terminal B from wires 34 and 35 and thereby releases a section locking relay RAES, which opens its contacts I) and c in the circuits for relays RACT and RAFS. The feed back circuit for relay RACT including wire 21 is also open at contacts'b of relays ZRI-IS and IRWP so that feed back impulses are not transmitted at this time.

is energized over channel l 0a to light lamp ,ITKE

on thetrack diagram. Relay 2RBP releases to restore signal 2RA tohstop and reenergizes. relays ZRGP and 2RAS..

When the train enters section AT, relays RATR, RATF, RATB, and 2RAI-I release, and relay RATF? initiates the transmission of an indi cation code by which relay ATK is energized over channel l2a to light lamp AKE. v

Whensection] IT is vacated, relays l' IR'and .I' IP pick up, relay RAES is reenergized by the closing of contact of relay, ITR, and the feed back circuit for relay RACT is prepared bythe closing of contact e of relay ITP and contact I; of relay RAES. Q}. .l I The code operation of relay LACT ceases when the train enters section 3T, due to the opening of contact e of relay 3TP, and when section 3T is vacated, the code operation of relay LACT'is resumed, and if relay RATR, respondsrelays RATF and RATB become energized and relay RACT is operated to generate feed back impulses which energize relay LA'IR. The closing of contact b of relay LATR restores relay to normal, causing relayLACT to become steadily energized, whereupon the system restores itself to the normal inactive condition as shown.

To clear signal ZRB, the operator moves levers ISW and Z'SG to' the right and then presses the starting button ZSTB. Relay ZSTS' is not onerate'd because its circuit is open at contacts 'of lever ISW, and only the code 234 is transmitted, this code operating relays IWS 61 These relays mayalso peoperated by successive codes so as; to enable the operator to verify theposit'ion of the switch 'b'e fore clearing the signal, as will readily be understood. Relay lWS operates switch IW torreverse, releasing relays lWP and INWP, and then energizing relay IWP reverse when-the switch assumes its reverse position, whereupon; relay I RWP becomes energized and by closing its contact d completes a circuit ior energizing relay REPS extendingover wire 36 toterminal B at contact d of relay Relay RBCT is released by the opening of back contact 0 of; relay RBPS; deenergizing section BT and releasing relay LBTB, whereupon relay LBTB picksup and relay LBTF releases to energize the traflicrelay LBFS, v The closing of front contact b of relay LBFS completes a circuit for periodically energizing relay LBCT so that relay LBCT which may be traced from, terminal B at contact of relay 3WLS, over wire 31, contacts b of relay LBTR and of the code transmitter 15CT, front contact b of relay LBFS, over Wire 38 and contact f of relay 3N'WP to Wire 40, or from wire 38 over contact 0 of relay 3TB, wire 39. and contact b of the directional stick relay LBWS- to wire 40. and thence .over back contact 0 of relay LBDS through relay LBCT to terminal C, is caused to supply '75 code to the rails of section BT at the right-hand end. The operation of relay RBTR in response to this code picks up relay RBTF which energizes transformer DTZ causing the code d ctor relay ZRBD to become energized. Relay RBCT is operated by impulses suppli d throu h transformer J2 by transformer DTZ to supply feed back im ulses to section BT, so that relay LBTF is en rgized to disconnect terminal B from chann l I21) a d to transmit an indication co e by which relay BTK is released an lamp PKE extinguished.

nRelay 2RBD now energizes theroute relay 2RBP by completing a circuit from terminal B over cont cts 6 of r la s ITR and I WLS, wire 4|, contact 0 of relav RBD, wire 42, the norma contact b of relav ZLHS. contact a of relay IRWP, contact e of relav IWP, and the reverse contact a of rela ZRl-TS throu h relay ZRBP to terminal 0. Relay ZRBP picks up and releases relay 2RAS to complete the circuit for'mechanism 2RBG which may be traced rom terminal B at front contact a of relav ZRBP, front contact 0 of r lav ZLAS, contact I) of relay ITER, back contact 0 of relay ZRAS, reverse contact d of relay IWP, wire 43, front contact 11 of relay ZRBD, wire 44, through the winding of mechani m QRBG. wire 45, front contact 11 of relay 2RBD, wire 46. contact 12 of rel y 2RBP and contacts c of relays ZLT-IS and ZRHS to terminal '0. The relative polarity of the current in this circuit is such that signal IZRB is caused to indic te proceed at slow speed.

When the train govern d by signal 2R3 enters section IT, relay ITR. releases to initiate operations simi ar to those above described in connection with signal ZRA, whereby signal 2RB is restored to stop and relay 2R -TS to normal.

The directional stick relay RBDS becomes energized upon the release of relav ITP over contacts f of relays IT? and IRWP, wire 41, and front contact. a of relay ZRBD, and when the train enters section B'I', relays RBTR, RBTF, and 2RBD release, relay 2RBD completing a stick circuit to hold relay REDS energized; The transmi sion of feed back impulses by transformer DT2'ceases and consequently relay LBTF releases, initiating the transmission of .anindication code to energize relay BTK over channel lzb and light lamp BKE to indicate the occupancy of section ET.

By operatingrelay 2RHS again to reverse before section ET is vacated, a following train may be admitted to the route. In this case the route relay ZRZBP is energized over contact 6 of relay RDBS, and mechanism ZRBG is sup similar to those already described .for section AT, and a description is therefore deemed unnecessary. 7

To clear signal 4LB, with the system in its normal inactive condition as shown, the operator reverses lever 33W and moves lever 4SG to the left and then presses button 4STB. The resulting operations in this case with respect to the track circuit system are similar to those described above for the similar but oppositely directed track circuit system by which signal ZRA is controlled, and involve the transmission of two control codes, one for reversing the traffic relay at the exit end of the block, relay RBFS in this case, which is controlled over channel 411, and the other for reversing theentering end signal control relay, which in this case is relay 4LHS, controlled over channel 51), and for also energizing relay 3W8 in the reverse direction over channel 3? in order to reverse switch 3W in the event this switch is in its normal position as shown. The reversal of relay RBFS causes relay RBCT to supply 75 code to the rails, of section BT, relay RBCT being energized over the circuit from terminal B over contact 1 of relay ZRAS and contact 0 of relay lTP, or from terminal B over contact I) of relay INWP, and thence over contact 0 of relay IWLS, wire 59, contact I) of the code transmitter T, contact a of relay REFS, contact 0 of relay RBDS, through relay RBCT to terminal C. In the preceding example, the two codes 234 and 26'! were issued in their relative order of code superiority, code 261 following code 234 in accordance with the normal mode of operation of the remote control system, but if the two codes are issued in that order in the .present case the track circuit system would be set into operation by the reversal of the traffic relay RBFS before the signal control relay 4LHS is reversed, and relay 4LHS being in its normal position would complete a circuit for relay LBCT from transformer J4 over wire 5| to terminal C at contact b of relay 3NWP or 4LHS, which would cause the transmission of feed back impulses to restore relay RBFS to normal and thereby restore the track circuit system to its inactive condition before relay 4LHS is reversed by code 261. It is therefore necessary to reverse the normal order of code transmission in this instance, and this is accomplished as shown in Fig. 1 by including a back contact e of relay 4STS in the initiating circuit for code 234.

It will be seen that if button 4STB is pressed when contacts 0 of levers 48G and 35W are closed, relay 4STS is picked up along with relay 4ST, and then relay 2ST is picked up over front contact 0 of relay 4STS but is rendered incapable of initiating code 234 by the opening of back contact e of relay 4STS. The closing of contact b of relay 4ST initiates code 261 for reversing relay 4LHS, whereupon relays GST and 4STS release, the release of relay 4STS allowing the transmission of the code 234 by relay 2ST, in which channel 4a is energized over contacts b of levers 4SG and 3SW to effect the reversal of relay RBFS.

The circuits by which signal 4LB is controlled .by the track circuit system are generally similar to those for the similar signal ZRB already described. In the present case, relay 3WP is reversed, relay 3NWP is released and relays ERWP and 4LBD are energized. Relay 4LBP picks up over a circuit which differs from that traced above in that it extends from wire 28 over contact 9 of relay 4LBD, wire 53, contact 19 of relay 4LI-IS and contact a of relay 3RWP. Contact c of relay 3NWP in the pick-up circuit for relay LWBS including wire 50. is nowopen, and relay LBWS is released by the opening of its stick circuit including wire 55, when relay ALAS is released by the operation of relay iLBP. Mechanism lLBG is energized over' a branch of the circuit traced above for mechanism lLAG which includes the reverse contact cl of relay EWP, wire 56, contact by of relay @LBD, wire the winding of mechanism @RBG, wire 58, contact (1 of relay lLBD to wire 33 and thence as already traced, to terminal C. The directional stick relay LBDS is picked up over the circuit including wire 50 when the train governed by signal iLB enters section 3'1, and functions like the corresponding relay RBDS already described.

It may be that to effect a meet, the operator will clear two signals such as ZRB and lLA or signals 2RA and lLB at the same time. The simultaneous clearing of signals ZRB and dLA may be accomplished in an obvious manner since they are governed independently by different codes but the simultaneous clearing of signals ERA and ALB requires consideration because the clearin of these signals involves the transmission of codes to the same two stations, but in different orders as already explained.

Assuming that lever 'lSW is normal and lever ZSG in its right-hand position, and that lever ESW is reversed and lever ASG is in its lefthand position, the operation of. button ZSTB will pick up relays 2ST, 'ZSTS, and i-ST, and the subsequent operation'of' button QSTB will pick up relay dSTS, while if button lSTB is operated first, relays 4ST, ASTS, and 2ST will be picked up by the operation of, button AS'IB and relay ZSTS by the operation of button ZSTB. In either case, code Zfiiis the first to issue, the initiating circuit. for ,code' 234 being open at back contact e of'relayfdSTS. Code 26'! reverses the signal control relay iLI-IS'by the energization of channel .ob over contact al-of lever GSG, and also reverses relay SWS by the energization of channel 3b, but the traffic relay LAFS is not operated at this time because channel 4b controlled by relay ZG'ES is now open at back contact In of relay ZSTS.

Relay AST and lS'I'S are released by relay 2615 in the usual manner in response tothe transmission of code 26'! to allow code 234 to follow, as above described inconnection with signal L-B, but as soon as relay 4STS releases, relay 4ST is reenergized over back contact d of relay lSTS and front contact 0 of relay ZSTS to store a second code 261 fortransmission following the delivery of code 234.1 Code 2234 reverses relay RBFS and also relay 2RI-IS, and also energizes relay IWS in the normal direction, the lever positions nowbeing such that channels la, 4a and la controlled by relay 23% are energized, and relay REES; energizes the track circuit system for section BTto effect the clearing of signal 4LB, relaylLI-IS having been reversed by the preceding code 26] as already described. Relays EST and ZSTS are released by relay ets in response to the transmission of coded-36 but since relay 551 is still energized, code 253 is again transmitted. Channel 4b controlled by relay acts is nowenergized over back contact I) of relay ZSTS, since this relaywas released by the preceding code 234, by which relay ZR'I-IS was energized. Relay LAFS is reversed-by the second code 2,6! to energize the track circuit system for section AT as required 14 for the clearing of signal ZRA, and channels 3b and 5b are also energized to maintain relays 3W8 and ALI-IS reversed.

t is to be noted that if channel 41) is energized when the first code 261 is transmitted, as would be the case if contact b of relay ZSTS were not included in its circuit, relay LAFS would be reversed by this code and would set the track: circuit system for section AT into operation but. since relay ZRHS at that time would be in its: normal position, relay RATC would be operated by a feed back impulse supplied by transformer DT! to pick up relay LA'IR, which relay would restore relay LAFS to its normal position. Relay LAFS would be reversed again by the second code 267 as above described, with the same end result. The purpose of contact I) of relay ZSTS is therefore merely to eliminate an idle operation of the wayside apparatus. b

Although I have herein shown'and described only one form of centralized traffic control apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and-scope of my. invention. 7

Having thus described my invention, what I claim is: I

1. In a centralized trafiic control system having signals at each end of a stretch of railway for governing trafiic movements into the stretch, a code type communication system having stations at said signal locations for governing said 'signals from a. central office, a traffic relay and a signal control relay at each station, 'a circuit for clearing each signal arranged to be energized in accordance with traific conditions in said stretch when the traflic relay at the other station is reversed provided the signal control relay controlled by each starting relay when energized for initiatin the transmission of a code for operating the signal control relay at the corresponding station to a position reflecting that of its lever or if such lever is in its normal position for operating the traflic lever at such station to reverse, provided the lever for the signal at the other station is reversed, means responsive to the momentary operation of each starting button for energizing the associated starting relay, and for also energizing the associated storing relay provided the signal lever associated therewith is reversed, means for releasin each energized starting relay and stor ing relay upon 1 the delivery of a code to the corresponding station, means controlled by the storingrelay for either station when energized for energizing the starting relay for the other station to thereby initiate the transmission of a second code, and means effective when both starting relays are energized for causing the code initiated bythe one having the associated storing relay energized to precede the code initiated by and a second station located at the opposite ends of a stretch of railway track, a signal at each station for governing traflie movements into said stretch, a first and a second panel at a control ofiice for the control of said stations each including a signal lever, a, starting button and a starting relay, a circuit controlled by each starting relay when operated for initiating the transmission of a code to the corresponding station by said code system, a circuit for operating each starting relay closed in response to the operation of the associated starting button, a circuit controlled by the starting button of each panel for operating the starting relay for the other panel if such button is operated when the signal lever associated therewith is in its signal clearing position, means dependent upon the relative order of transmission of the codes transmitted when both starting relays are operated for controlling one signal or the other in accordance with the position of its signal lever, means normally effective to cause the code for the first station to precede the code for the second station when said two codes are initiated by the operation of the starting button of the first panel, and means for reversing the normal order of transmission of said codes when they. are initiated by the operation of the starting button of the second panel.

3. In a centralized trafiic control system, a code type communication system having a first and a second station located at the opposite ends of a stretch of railway track, a, signal at each station for governing traific movements into said stretch, a first and a second panel at a central office for the control of said stations, each including a signal lever, a starting button, a starting relay and a storing relay, a circuit controlled by each starting relay when operated for initiating the transmission of a code to the corresponding station by said code system, a circuit for operating each starting relay closed upon the operation of the associated starting button, a circuit for operating each storing relay when the associated starting button is operated provided the signal lever of the same panel is in its signal clearing position, a circuit closed by each storing relay when operated for operating the starting relay of the other panel provided the storing relay of such other panel is in its normal position, whereby codes may be initated for transmission to both stations by the operation of either starting button, means dependent upon the relative order of transmission of said codes for controlling one signal or the other in accordance with the position of its signal lever, means normally effective when both starting relays are operated for causing the code for the first station to precede the code for the second station, and means controlled by the storing relay of the second panel when operated for reversing the relative order of transmission of said two codes.

4. In a centralized traffic control system, a code type communication system having a first and a second station located at the opposite ends of a stretch of railway track, a signal at each station for-governing traffic movements into said stretch, a first and a second panel at a central office for the control of said stations,'each in cluding a signal lever, a starting button, a starting relay and a storing relay, a circuit controlled by each starting relay when operated for initiating the transmission of a code to the corresponding station by said code system, a circuit for operating each starting relay closed upon the operation of the'associated starting button, a, circuit for operating each storing relay when the associated starting button is operated provided the signal lever of the same panel is in its signal clearing position, a circuit closed by each storing relay when operated for operating the starting relay of the other panel provided the storing relay of such other panel is in its normal position, whereby codes may be initiated for transmission to both stations by the operation of either starting button, means dependent upon the relative order of transmission of said codes for controlling one signal or the other in accordance with the position of its signal lever, means normally effective when both starting relays are operated for causing the code initiated by the starting relay of the first panel to precede that initiated by the starting relay of the second panel, means controlled by the storing relay of the second panel when operated for causing the code initiated by the associated starting relay to precede said code initiated by the starting relay of the first panel, and means controlled by the storing relay of the first panel when both storing, relays are operated for causing the reoperation of the starting relay for the second panel to effect the transmission of a second codev to said second station.

5. In a centralized traffic control system, a code type communication system having a first and a second station located at the opposite ends of a stretch of railway track, a signal at each station for governing traflic movements in accordance with traffic conditions in said stretch, a signal control relay at each station for manually governing the adjacent signal, a traffic relay at each stati-on,'one of which when reversed establishes one direction and the other the opposite direction for traffic movements into said stretch, a control panel at a central office for each station each including a signal lever, a starting button, a starting relay and a storing relay, means for operating each starting relay when the starting button of the same panel is operated, and also when the storing relay of the other panel is operated, means controlled by each starting relay when operated for initiating the transmission of a code by said code system by which the signal control relay at the corresponding station is operated when its signal lever is in its signal clearing position or by which the traific relay at such station is operable to reverse provided the signal lever for the signal at the other station is in its signal clearing position, means governed by each signal control relay in its normal position for restoring the trafiic relay at the other station to normal, means for operating each storing relay in response to the operation of the associated starting button provided the signal lever for the same panel is in its signal clearing position, and means governed by at least one of said storing relays for governing, the relative order of transmission of said two codes initiated by said starting relays when either signal lever is in its signal clearing position so that for either direction of trafiic movement that one of the codes by which the signal control relay is operated precedes the one by which the traffic relay at the other station is reversed.

6. In a centralized trafiic control system, a code type communication system having a first and a Second station located at the opposite ends of a stretch of railway comprising two parallel tracks, signals at said stations for governing traffic movements into'said stretch, a signal control relay and a traflic relay at each station, circuits for the signal at the first station controllable in 17 accordance with traffic conditions in one of said tracks by the traffic relay at the second station and by the signal control relay at the first station, circuits for the signal at the second station controllable in accordance with trafiic conditions in the other track by the traific relay at the first station and by the signal control relay at the second station, a control panel at a central office for each station each including a signal lever and a starting button, a starting relay in each panel operable by the associated button, means controlled by each starting relay when operated for initiating the transmission of a code by said code system by which the signal control relay at such station is operable in accordance with the'position of its signal lever or'by which the traffic relay at such station is operable to reverse provided the signal lever for the signal at the other station is in its signal clearing position, a circuit controlled by each signal control relay in its normal position effective when the corresponding track in said stretch is unoccupied for restoring the trafiic relay at the other station to its normal position, a storing relay in each panel, a circuit for operating each storing relay when the associated starting button is operated provided the signal lever for the same panel is in its signal clearing position, a circuit controlled by each storing relay when operated for operating the starting relay for the other panel, means effective when the storing relay of the panel for the second station is operated to delay the transmission of a code to the first station until such storing relay is released, means for restoring each operated storing relay to its normal position along with the associated starting relay upon the transmission of the corresponding code, and means effective if the storing relay of the first panel is in its operated position when the starting relay for the second panel is restored to normal for reoperating said starting relay.

7. In a centralized traffic control system, a code type communication system having a first and a second station located at the opposite ends of a stretch of railway track, a reversible coded track circuit system having a track relay at each end adapted to reflect traffic conditions in said stretch and having a transmitter relay at each end which in one position connects a source of current to the rails of the stretch and in another position conditions the adjacent track relay to respond to current received over the rails of the stretch, a trafiic relay and a signal control relay at each station, a signal at each station for governing traffic movements into said stretch, a circuit for clearing each signal controlled by the adjacent signal control relay in accordance with the periodic operation of the adjacent track relay, circuits rendered effective when either traflic relay is in its operated position for causing the code transmitter adjacent thereto to supply periodically interrupted current to the track rails of the stretch, means effective when the trafiic relay and signal control relay at the second station are both in their normal positions for maintaining the code transmitter at that end of the stretch in said one position to supply steady current to the track rails, a first repeating relay controlled over a front contact of the track relay at the first station, a second repeating relay controlled over a back contact of said track relay and a front contact of said first repeating relay, a circuit for operating the trafiip relay at the first station controlled over back contacts of the adjacent track relay and of said first repeatin relay, said circuit also including a front contact of said second repeating relay, a restoring circuit for each trafiic relay effective to restore such relay to its normal position when the adjacent track relay becomes energized, a signal lever for each signal located at a control office, and means including said communication system for operating each signal control relay to a position which reflects that of the corresponding signal lever and for also operating the traflic relay at the second station to its reverse position when the signal lever for the signal at the first station is in its signal clearing position.

8. In a centralized traific control system, a code type communication system having a first and a second station located at the opposite ends of a stretch of railway track, a signal at each station for governing traffic movements into said stretch, a first and a second panel at a central ofiice for the control of said stations each-including a signal lever, a starting button, a starting relay and a storing relay, indication means at said oflice controlled by said communication system reflecting traffic conditions in said stretch, means for operating eachstarting relay when the associated starting button is operated and also when the storing relay for the other panel is operated but only if said indication means indicates that the stretch is unoccupied, means for operating each storing relay when the associated starting button is operated provided the signal lever of the same panel is in its signal clearing position, a circuit controlled by each starting relay when operated for initiating the transmission of a code to the corresponding station by said communication system, means controlled jointly by the codes transmitted to said stations when the signal lever of either panel is in its signal clearing position for clearing the signal at the corresponding station, and means for restoring each operated storing relay to its normal position along with the associated starting relay upon the transmission of a code to the correspondingstation.

FRANK T. PASCOE.

No references cited. 

